The Placencia Lagoon - Coastal Zone Management Authority and ...

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MATERIALS AND METHODS The Coastal Zone Management Authority and Institute provided the equipment and materials that were utilized in this study. These include the following: (a) a 28 feet skiff equipped with two 115 hp outboard engines, global positioning system (GPS) and echo sounder. (b) Two water quality multiparameter sonde [H20 and DataSonde 4a manufactured by Hydrolab Corporation]. (c) A unidirectional current meter manufactured by Qualimetrics Inc. (d) Graduated PVC pipe (The measuring Pole) The objectives of this research were accomplished using the methods and data analyses described below. Comprehensive Literature Review Throughout the duration of this study, the author was fully engaged in reviewing literature pertinent to the Placencia Lagoon. This step was necessary to collate relevant information and identify the information gaps. It is believed that the existing information gaps limit our understanding of how the lagoon functions as a system, how it reacts to hydrological, meteorological and tidal forces. Furthermore, it is not clear how the lagoon responds ecologically to anthropogenic inputs of sediment, nutrients and pollutants. Data Collection Water Quality Four water quality surveys were conducted in the Placencia Lagoon on the following dates: Survey 1 April 5, 2001 Survey 2 May 31, 2001 Survey 3 March 12, 2003 Survey 4 July 17,2003 Sampling stations were randomly selected in the study area on all surveys. At total of 59 stations were sampled on Survey 1; 65 stations on Survey 2; 53 stations on Survey 3 and 25 stations on Survey 4. The water quality multiparameter sonde were used to record surface and bottom measurements of temperature, pH, Specific conductivity, salinity, dissolved Oxygen, depth and turbidity. Prior to any measurement in the field the sonde was properly calibrated in the CZMAI Laboratory. The salinity sensor was calibrated using the synthetic seawater method described in section 1.1H of Parsons et al. (1984). The accuracy of the salinity sensor is ± 0.1 parts per thousand. The pH probe was calibrated using a three-point calibration procedure with pH buffers 5, 7 and 10. The accuracy of the pH probe is ± 0.2 units. 5
The turbidity sensor was calibrated with known concentrations of formazine solution. The accuracy of the sensor was ± 2.0 NTU. The depth sensor (a pressure transducer) was regularly calibrated in the field to compensate for changes in water level, wave height and barometric pressure. Unlike the aforementioned sensors, the temperature sensor is factory calibrated with an accuracy of ± 0.05 °C hence, there was no need to calibrate this senor in the laboratory or the field. Bathymetry A special field bathymetric survey was conducted on July 18, 2003 in which 202 soundings were recorded in the Placencia Lagoon. The depth measurements were taken using the pressure transducer installed on the multiparameter sonde and the echo sounder aboard the CZMAI research vessel (Submarine 2). A graduated PVC pipe was used to measure the depths in extremely shallow but critical parts of the lagoon. As with the water quality stations, all bathymetric soundings were geo-referenced using the global positioning system. Data Analyses The data recorded on paper and on the multiparameter sondes were uploaded to Microsoft Excel worksheets. Using this software, basic mathematical operations were conducted to prepare several charts and tables. Furthermore, water quality variables were analyzed with descriptive statistics to determine means, ranges, standard deviation and variance. A non-drift krigging interpolation method was used to create contour maps using Surfer 7.0. Maps of this type illustrate the bathymetry, spatial distribution of temperature and salinity within the study area. Considering that most of the data obtained in this research are geo-referenced data, the final maps and graphic illustrations were produced using ArcView GIS 3.1. 6
Page 2 and 3: Characterization of a Tropical Estu
Page 4 and 5: ACKNOWLEDGEMENT The preparation of
Page 6 and 7: EXECUTIVE SUMMARY There is growing
Page 8: OBJECTIVES To identify and document
Page 14 and 15: inundation during the rain season.
Page 16 and 17: Salinity The salinity of the Southe
Page 19: Major Land Use and Activities in th
Page 23 and 24: Table 2a. Shrimp Mariculture produc
Page 26 and 27: Temperature °C 30.20 30.00 29.80 2
Page 28 and 29: The salinity measurements within th
Page 30 and 31: Turbidity The mean turbidity levels
Page 32 and 33: The salinity maps presented in Appe
Page 34 and 35: CONCLUSIONS The characterization of
Page 36 and 37: Huntington, T., Dixon, H. 1997. A R
Page 38: APPENDIX I Temperature Distribution
Page 48: Abbreviations and Notations BNMS Be

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